Vacuum brake system for railway trains



Aug. 11, 1964 w. H. GLASS 3,

VACUUM BRAKE SYSTEM FOR RAILWAY TRAINS Original Filed Feb. 15, 1960 INVENTOR. 46 T Villiam H Glass United States Patent O 3,144,277 VAiIUUM BRAKE SYSTEM FOR RAILWAY TRAINS Wiiiiam H. Glass, Pittsburgh, Pa., assignor to Westinghouse Air Brake Company, Wiimerding, Pin, a corporation of Pennsylvania Griginal application Feb. 15, 1960, Ser. No. 8,679, now Patent No. 3,114,498, dated Dec. 17, 1953. Divided and this application (Bot. 24, 1962, Ser. No. 232,693 7 Claims. (Cl. 303-12) This invention relates to combined pressure and vacuurn brake systems for railway trains of the type having vacuum pumps or exhausters driven by diesel or other types of internal combustion engines, and more particularly to such brake systems having the brake control means arranged to control the loading and unloading apparatus for the vacuum pumps or exhausters, this application being a division of copending application, Serial No. 8,679, filed February 15, 1960, now Patent 3,114,498.

Until recently the vacuum exhausters that are provided on railway locomotives used for hauling railway cars having vacuum type brake equipment were driven by electric motors controlled manually by the locomotive engineer by means of a hand-operated switch located in the power supply circuit of the motor for effecting the starting and stopping of the motor and the vacuum exhauster driven by the motor.

In the newer types of exhauster installations on modern diesel-electric locomotives, two exhausters are directly driven through some suitable mechanical connection by the diesel engine of the locomotive so that the exhausters are continuously operated so long as the diesel engine is running. Where two or more locomotive units, each of which is provided with two exhausters, are used to haul a train, the combined capacity of the two exhausters on each unit is required to effect a release of the vacuum brakes on the cars in the train. However, the combined capacity of all of the exhausters on the several units exceeds the demand after the brakes have been released and the train is running along the track since, at this time, the exhausters are required to merely maintain the vacuum brake pipe through the train against leakage.

The heretofore used conventional type of manual startstop exhauster control cannot be conveniently employed on the new types of continuously driven exhauster installations. Consequently, some method and means for loading and unloading an exhauster is necessary.

In some of these newer types of continuously driven ex'hauster installations the loading and unloading of one of the exhausters on each locomotive unit has been ef-. fected by an unloading device that holds open the inlet valve of the exhauster.

It is a well-known and common practice to maintain in the crankcase chamber of exhausters and compressors a sub-atmospheric pressure or vacuum in order to reduce the susceptibility of the lubricating oil from the crankcase chamber, which has been splashed upon the cylinder wall by the crankshaft, to pass around the piston rings of the piston to the cylinder chamber as compared to an arrangement in which the exhauster crankcase chamber is maintained ,at atmospheric pressure.

It will be understood that maintaining the exhauster crankcase chamber at a sub-atmospheric pressure produces equalization of pressure on the opposite faces of the exhauster piston whereas with atmospheric pressure present in the crankcase chamber the differential of pressure acting on the exhauster piston is in a direction to force the lubricating oil past the piston rings on the piston to the exhauster cylinder chamber. Therefore, an equalization of pressures on the opposite faces of the piston tends to reduce the passage of oil past the piston rings on the piston.

Essentially, the invention comprises a vacuum brake system for railway trains which brake system has a fluid pressure operated exhauster unloading valve device under the control of the usual brake control valve located in the locomotive cab for controlling the operation of the brakes on the train. This fluid pressure operated unloading valve device is operable to control the opening and closing of a communication between an exhauster cylinder chamber and atmosphere.

In all positions of the brake valve except the Release position, (sometimes called Release and Charging position) fluid under pressure, such as air, is supplied from a main reservoir to the fluid pressure operated unloading valve device to cause it to connect the exhauster cylinder chamber to atmosphere.

In its Release position, the brake valve establishes a communication through which air under pressure from the unloading valve device is vented to atmosphere, thereby causing the unloading valve device to close the communication between the exhauster cylinder chamber and atmosphere to load the exhauster.

in the accompanying drawing:

FIG. 1 is a diagrammatic view, mainly in section, of a vacuum brake system for a railway train which system includes a fluid pressure operated unloading valve device shown in a so-called load position for loading one of two diesel engine continuously driven vacuum exhausters, and a manually operated control valve device, illustrative- 1y shown as a vacuum type brake valve device, for controlling the unloading valve device.

FIG. 2 is a partial sectional view of the brake valve device of FIG. 1, showing the fluid pressure connections established thereby in the position to effect operation of the fluid pressure operated unloading valve device shown in FIG. 1 to unload one of the two diesel engine driven vacuum exhausters.

Description In FIG. 1 of the drawing the combined vacuum and fluid pressure brake system shown for a railway train comprises a main fluid pressure storage reservoir 1 which may be charged by a fluid compressor (not shown), a feed valve device 2, a vacuum brake pipe 3, a manually operated vacuum type brake valve device 4, a vacuum reservoir 5, two vacuum pumps or exhausters 6 and 7, each of which is directly driven through some suitable mechanical connection by a diesel engine (not shown) on a railway locomotive so that these exhausters are continuously operated so long as the diesel engine, which constitutes the prime mover of the locomotive, is running, and a fluid pressure operated loading and unloading valve device '8 under the control of the manually operated brake control valve device 4 for eiiecting the loading and unloading of the exhauster 7.

The brake valve device 4 may be identical in construction to the brake control valve device disclosed in United States Patent No. 1,454,569, issued May 8, 1923 to Thomas H. Thomas and assigned to the assignee of this application.

Briefly, however, the brake valve device 4 comprises a body 9 having a relay type release valve portion 10. Release valve portion 10 is adapted to control communication between a vacuum reservoir pipe 11, which pipe is connected to the vacuum reservoir 5, and the vacuum brake pipe 3. The vacuum brake pipe 3 is connected to a vacuum brake pipe on the cars in a train which cars are provided with a suitable vacuum brake equipment for controlling the braking thereof. The brake valve device 4 further comprises a relay type application valve portion 12 for controlling communication between the vacuum brake pipe 3 and atmosphere, a rotary valve 13 and a drum valve 14 each adapted to J be operated by an handle which is operatively connected to a rotary valve stem 16 to which the rotary and drum valves are connected for rotation therewith, a rotary valve seat 17, and a pipe bracket 18.

As shown in FIGS. 1 and 2 of the drawing, there are seven passageways opening through respective corresponding ports at the face of the rotary valve seat 17, the passageways and ports being respectively designated by the numerals 19, 29, 21, 22, 23, 24 and 25.

The two ports 19 and 20 are connected respectively by correspondingly numbered passageways in the rotary valve seat 17 and the body 9 of the brake control valve device 4 to the release valve portion 10 and the application valve portion 12.

The port 21 is connected by its correspondingly numbered passageway in the rotary valve seat 17, the body 9 of the brake control valve device 4, and the pipe bracket 18 to a tapped port opening at the face of the pipe bracket and into which is received one threaded end of the vacuum reservoir pipe 11.

The port 22 is an atmospheric exhaust port connected to atmosphere by its correspondingly numbered passageway.

The port 23 is connected by its correspondingly numbered passageway in the rotary valve seat 17, the body 9 of the brake control valve device 4, and the pipe bracket 18 to a tapped port opening at the face of the pipe bracket and into which is received one threaded end of an application cylinder pipe 26. The opposite end of the application cylinder pipe 26 is connected to a distributing valve device (not shown) which is a part of the usual combined vacuum and fluid pressure brake system used on railway locomotives but forms no part of the present invention. The communication provided by the application cylinder pipe 26 between the manually operated brake control valve device 4 and the distributing valve device provides a conduit through which fluid under pressure may be supplied from the feed valve device 2 to an application cylinder chamber in the distributing valve device when the handle 15 of the manually operated brake control valve device 4 is moved to an emergency postion. The supply of fluid under pressure from the feed valve device 2 to the application cylinder chamber of the distributing valve device operates the application portion of the distributing valve device to provide a higher pressure in the brake cylinders on the locomotive while an emergency brake application is in effect than is obtained when a service brake application is made.

The port 24 is connected by its correspondingly numbered passageway in the rotary valve seat 17, the body 9 of the brake control valve device 4, and the pipe bracket 18 to a tapped port opening at the face of the pipe bracket and into which is received one threaded end of an unloader pipe 27. The opposite end of the unloader pipe 27 is connected to the fluid pressure operated loading and unloading valve device 8.

The port is connected by its correspondingly numbered passageway in the rotary valve seat 17, the body 9 of the brake control valve device 4, and the pipe bracket 18 to a tapped port opening at the face of the pipe bracket and into which is received one threaded end of a feed valve pipe 28. A branch 25a of the passageway 25 in the body body 9 opens into the chamber in which rotary valve 13 is disposed. The opposite end of the feed valve pipe 28 is connected to an outlet or delivery port of the feed valve device 2. The feed valve device 2 also has an inlet or supply port to which is connected one end of a supply pipe 29, the opposite end of which is connected to the main fluid pressure storage reservoir 1.

The vacuum pumps or exhausters 6 and 7 are, for simplicity, each shown in FIG. 1 of the drawing as comprising only one cylinder. It should be understood, however, that the pump or exhauster 6 may be of the multiple cylinder type having two or more cylinders and the pump or exhauster 7 may be of the compressorexhauster type having one or more cylinders for compressing atmospheric air and supplying it under pressure to the main fluid pressure storage reservoir 1 through a suitable conduit mean (not shown), and one or more cylinders for exhausting fluid under pressure from or pumping a vacuum in, such as the vacuum reservoir 5.

The exhauster 7 shown in FIG. 1 0f the drawing is identical in construction to the exhauster 6 except the exhauster 7 is so arranged, as hereinafter explained as to be loaded and unloaded by operation of the fluid pressure operated loading and unloading valve device 8 in a manner hereinafter described.

As shown illustratively, each exhauster comprises a cylinder body 30 having a piston bore 31 therein. Slidably operable in the piston bore 31 is an exhauster piston 32. In order to reduce oil leakage past the piston 32 into a cylinder chamber 33 located above the exhauster piston 32, the piston 32 is provided with three spacedapart piston rings 34 each having sealing and sliding contact with the wall of the bore 31 in which the piston operates.

A cylinder head 35 is secured to the upper end of the cylinder body 30 by any suitable means (not shown) there being an annular resilient gasket 36 interposed between the upper end of the cylinder body 30 and the cylinder head to prevent leakage of atmospheric air into the cylinder chamber 33.

Located in the left-hand side of the cylinder head 35 is an inlet valve chamber 37 which is constantly in communication with the cylinder chamber 33 through a plurality of ports 38 formed in a threaded plug 39 which is screwed into a threaded counterbore 40 formed in the cylinder head. The cylinder head 35 is provided with a counterbore 41, coaxial with the threaded counterbore 40, into which is pressed a hollow annular inlet valve seat 42. A passageway 43 formed in the cylinder head 35 opens at one end into the bottom of the counterbore 41 and at the opposite end is screw-threaded to receive one branch of a pipe 44 which is connected to the vacuum reservoir 5.

Second and third branches of the pipe 44 are connected respectively to a screw-threaded end of a passageway 45 formed in a crankcase 46 of each exhauster. The opposite end of the passageway 45 opens into a crankcase chamber 47 cooperatively formed by the crankcase 46, the lower face of the piston 32 and the cylinder body 30, the lower end of which body is secured to the crankcase 46 by any suitable means (not shown), there being a resilient gasket 48 interposed between the cylinder body 30 and the crankcase 46.

Communication between the passageway 43 and the inlet valve chamber 37 is controlled by a fluted annular flat disc inlet valve 49 which is urged upward towards seating contact with the valve seat 42 by a spring 50 in terposed between the inlet valve and the threaded plug 39.

Located in the right-hand side of the cylinder head 35 is a discharge valve chamber 51 which is open to atmosphere through a passageway 52 formed in the cylinder head. Communication between the cylinder chamber 33 and the discharge valve chamber 51 is controlled by a fluted annular flat disc discharge valve 53 disposed in the discharge valve chamber 51 and normally urged into seating contact with an annular discharge valve seat 54 by a spring 55 interposed between the discharge valve 53 and the upper wall of the discharge valve chamber 51. The discharge valve seat 54 is pressed into a bore 56 formed in a threaded plug 57 which is screwed into a threaded counterbore 58 formed in the cylinder head 35.

The exhauster piston 32 is connected by means of a connecting rod 59 to a crankshaft (not shown) which is mechanically driven by the diesel engine on the locomotive so that the exhauster piston 32 is constantly reciprocated within the piston bore 31 in the cylinder body 30 while the diesel engine is running.

The fluid pressure operated loading and unloading valve device 8 preferably comprises a casing section or body 60 having therein two chambers 61 and 62 connected by a bore 63 and a coaxial counterbore 64 of larger diameter. The casing section or body 60 is provided with a passageway 65 which constantly connects the chamber 61 to atmosphere, and two threaded bores 66 and 67, each of which opens from the chamber 62 to the exterior of the body. The threaded bore 66 is coaxial with the bore 63 and counterbore 64 and slightly larger in diameter than the counterbore 64. The threaded bore 67 has its axis arranged at a right angle to the axis of the bore 63 and counterbore 64. Screw threaded into the threaded bore 67 is one end of a pipe 68, the opposite end of which is screw threaded into a threaded end of a passageway 69 formed in the cylinder body 38 of the exhauster 7 and opening at its opposite end into the upper end of cylinder chamber 33 of this exhauster above the top dead center position of the piston 32.

Mounted within the body 60 of the fluid pressure operated loading and unloading valve device 8 is a loading and unloading valve mechanism comprising a number of parts which are assembled as follows:

First, two springs 78 and 71 are placed in corresponding truncated cone-shaped cavities 72 and 73, respectively. These cavities are formed in a spring retaining member 74 so that the lower end of these springs rests on the spring retaining member. The spring retaining member 74 also has a central threaded bore 75, two bores 76 and 77 coaxial respectively with the cavities 72 and 73 and opening at the bottom thereof, and two counterbores 78 and 79 coaxial respectively with the bores 76 and 77. Therefore, subsequent to placing the springs 70 and 71, respectively, in the truncated cone-shaped cavities 72 and 73, two apertured annular flat disc valves 80 and 81 are placed in the corresponding counterbores 78 and 79 respectively so that the lower sides thereof contact respectively the upper end of the springs 70 and 71.

Next, a valve seat member 82 having a flange 83 and a central bore 84 is assembled to the spring retaining member 74 by means of a threaded stud 85 and a nut 86. The threaded stud 85 extends through the bore 84 in the valve seat member 82 and is screwed into the central threaded bore 75 in the spring retaining member 74. The nut 86 is screwed onto the threaded stud 85 thereby forcing the valve seat member 82 against the spring retaining member 74 and also against the flat disc valves 80 and 81 which are yieldingly biased by the respective springs 70 and 71 into contact with flat annular valve seats 87 and 88 formed on the valve seat member 82 on the side thereof that is in contact with the spring retaining member 74.

As shown in FIG. 1 of the drawing, the valve seat member 82 has extending therethrough, in addition to the central bore 84, four bores 89 of equal diameter, two opening respectively at the face of each of the flat annular valve seats 87 and 88. The purpose of the bores 89 will be hereinafter made apparent.

The stud 85 has a stem portion 98 that extends above the nut 86. Following tightening of the nut 86 on the stud 85 to secure the valve seat member 82 against the spring retaining member 74, a spring 91 is disposed about the nut 86 and stem portion 90 with one end resting against the upper side of the valve seat member 82. An apertured offset spring seat in the form of a collar 92 is then placed so that it rests against the end of the spring 91 opposite the end that rests against the upper side of the valve seat member 82. A force is now applied to the spring seat 92 by any suitable means to compress the spring 91 and move the spring seat toward the nut 86 until the stem portion 98 of the stud 85 extends through the aperture in the spring seat far enough for a cotter pin 93 to be inserted in a bore in the stem portion 90. Upon removal of force from the spring seat 92, the spring 91 will be retained interposed between the valve seat member 82 and the spring seat.

When a first assembly, comprising the spring retaining member 74, the springs 70 and 71, the flat disc valves and 81, the valve seat member 82, the stud 85, the nut 86, the spring 91, the spring seat 92 and the cotter pin 93, has been assembled, as described above, the spring retaining member end of the assembly is introduced into the open end of the threaded bore 66 in body 68. The assembly is then shoved downward with the spring retaining member 74 aligned coaxially with the bore 63 in the body 68 until until a tapered surface 94 formed on the lower end of the spring retaining member 74 contacts an identical tapered surface 95 formed on the body 60 adjacent the lower end of the bore 63 and the parts of the assembly assume the position shown in FIG. 1. T o retain the assembly in the position shown in FIG. 1, a hollow valve plug or bushing 96, which is provided adjacent its upper end with external screw threads and adjacent its lower end with several arcuately arranged openings 97, is now screwed into the screwthreaded bore 66 in the body 60. The threaded end of the bushing 96 is provided with a pair of slots 98 to permit the insertion therein of a rod or bar to which a manual force may be applied to turn the bushing 96 whereby it slower end, by acting on the flange 83 which is formed integral with the valve seat member 82, forces this member and the spring retaining member 74 downward until an air tight seal is made between the tapered surface 94 on the spring retaining member 74 and the tapered surface 95 formed on the body 69.

The annular flat disc valves 80 and 81 are moved away from their respective valve seats 87 and 88 to establish a fluid pressure communication between the chambers 61 and 62 by an unloader plunger 99 which will now be described in detail. The unloader plunger 99 comprises a hollow cylindrical member 101) which has formed integral therewith at one end a flange 191 and at the op posite end a stem 102. The flange 101 is provided with a central counterbore 103 and carries a plurality of de pending fingers 104.

Therefore, after the bushing 96 has been tightened, as by means of a rod or bar, as mentioned above, the unloader plunger 99 is inserted into the upper end of the bushing 96 and so aligned that, as it is lowered in the bushing, the spring seat 92 will be received in the central counterbore 163 and the depending fingers 184 will extend through corresponding bores 89 in valve seat member 82 and contact the upper sides of the flat disc valves 80 and 81.

Subsequent to properly positioning the unloader plunger 99 within the bushing 96, a spring 185 is disposed about the stern 192 with one end resting against a shoulder 196 formed on the unloader plunger 99. An apertured spring seat 107 having a collar 1118 is next slipped over the end of the stem 182 so that the collar 188 rests against the end of the spring 185 opposite the end that rests against the shoulder 186. A force is now applied to the spring seat by any suitable means to compress the spring 105 and move the spring seat 107 toward the shoulder 196 until a retaining snap ring 199 can be inserted in a recess formed on the stem 182 adjacent the upper end thereof. Upon removal of force from the spring seat 187, the spring 105 will be retained interposed between the shoulder 186 and the spring seat 187.

Following the removal of force from the spring seat 167, an inverted cup-shaped member 110 is placed upon the collar 188 of the spring seat 187.

Next, a second assembly is made up as follows:

First, a bushing 111, having a bore 112 slightly larger than the diameter of the hollow cylindrical member 191) of the unloader plunger 99, the collar 198 and the cupshaped member 110, is pressed into a bore 113 formed in an unloader piston body 114 until a shoulder 115 formed on the exterior of the bushing 111 abuts the unloader piston body at the exterior end of the bore 113. A second bushing 116 is next pressed into a counterbore 117 formed in the unloader piston body 114 coaxial with the bore 113. Thereafter, an unloader piston 118, which is provided with a resilient gasket ring 119, is pushed into the bushing 116 whereupon the gasket ring 119 will have sealing and sliding contact with the wall of the bore in the bushing in which the unloader piston operates. Subsequent to placing the unloader piston 118 within the bore in the bushing 116, a cap nut 120, which is provided with a central screw-threaded bore 121 to receive the end of the pipe 27 and to which has been previously assembled a screen 122 and a screen retainer 123 pressed into a bore 124 in the cap nut, is screwed into a screw-threaded bore 125 formed adjacent the upper end of the unloader piston body 114 and coaxial with the bores 113 and 117 therein.

The lower end of the unloader piston body 114 has a second screw-threaded bore 126 which is coaxial with the bores 113, 117 and 125 in the body. The internal screw threads in the bore 126 are substantially the same size as the external screw threads which are formed on the upper end of the hollow bushing 96 and extend above the top of body 60 after the hollow bushing 96 has been screwed into the screw-threaded bore 66 in the body 69.

When the second assembly, comprising the unloader piston body 114, the bushings 111 and 116, the unloader piston 118 and the cap nut 120, has been assembled, as just described, the exterior end of the bushing 111 is slipped over the inverted cup-shaped member 119 and the entire assembly pushed downward until the bottom of the unloader piston body 114 is aligned with the upper end of the hollow bushing 96. The assembly is then rotated so that the unloader piston body 114 is screwed onto the upper end of the hollow bushing 96 until the bottom of the unloader piston body 114 is brought into contact with the upper end of the body 61).

When the parts of the fluid pressure operated loading and unloading valve device 8 have been assembled, as just described, they will occupy the position in which they are shown in FIG. 1 of the drawing.

Operation In operation, let it be assumed that the diesel engine which drives the exhausters 6 and 7, and which also constitutes the prime mover of one unit of a multi-unit railway locomotive, is stopped, and that the main fluid pressure storage reservoir 1 and the vacuum reservoir are at atmospheric pressure. Further assume that the handle and the rotary valve 13 of the manually operated brake control valve device 4 occupy their Release and Charging position, in which position they are shown in FIG. 1 of the drawing. While in its Release and Charging position, as shown in FIG. 1 of the drawing, a first cavity 127 in the rotary valve 13 connects the port 24 in the rotary valve seat 17, which port 24 is connected by its correspondingly numbered passageway in this rotary valve seat, the body 9 and the pipe bracket 18 of the brake control valve device 4 to the unloader pipe 27, to the atmospheric exhaust port 22. Also, at this time, a second cavity 128 in the rotary valve 13 connects the port 21 in the rotary valve seat 17, which port 21 is connected by its correspondingly numbered passageway in the rotary valve seat 17, the body 9 and the pipe bracket 18 to the vacuum reservoir pipe 11, to the port 20 in the rotary valve seat 17, which port 20 is connected by its correspondingly numbered passageway in the rotary valve seat and the body 9 to the application valve portion 12. Furthermore, when the rotary valve 13 occupies its Release and Charging position, a passageway 131), which extends through the rotary valve 13, registers with the port 19 in the rotary valve seat 17, which port 19 is connected by correspondingly numbered passageways in the rotary valve seat and body 9 to the release valve portion 10. Hence, when the rotary valve 13 occupies the position shown in FIG. 1, fluid under pressure is completely vented from a chamber 131 above the piston 118 within the fluid pressure operated loading and unloading valve device 8 through the unloader pipe 27, port 24 and its correspondingly numbered passageway in the rotary valve seat 17, body 9 and pipe bracket 18, cavity 127 in the rotary valve 13 and exhaust port 22. Furthermore, in this position of the rotary valve 13, fluid under pressure is completely vented from a chamber 132 beneath an operating piston 133 in the release valve portion 14), since it has been assumed that the main fluid pressure storage reservoir 1 is at atmospheric pressure, through respectively, port 19 and its correspondingly numbered passageway in the rotary valve seat 17 and the body 9, and passageway in the rotary valve 13 to the rotary valve chamber, and thence through the branch 25a to the passageway in the body 9 that is connected to the port 25 and pipe 28, pipe 28, feed valve device 2, and pipe 29 to the main fluid pressure storage reservoir 1. Since it has also been assumed that the vacuum reservoir 5 is at atmospheric pressure at this time, only atmospheric pressure is present in the communication that extends from a chamber 134 beneath an operating piston 135 in the application valve portion 12 through the correspondingly numbered passageways in the body 9 and rotary valve seat 17 to the port 2! opening at the face of the rotary valve seat and thence through the cavity 128 in the rotary valve 13 to the port 21 also opening at the face of the rotary valve seat 17, and then through the correspondingly numbered passageway in the rotary valve seat, the body 9, and the pipe bracket 18 to the vacuum reservoir pipe 11 which is connected to the vacuum reservoir 5.

Consequently, in view of the absence of fluid under pressure in the chamber 131 above the piston 118 in the fluid pressure operated loading and unloading valve device 8, the spring 91 is effective to move the unloader plunger 99 and unloader piston 118 to the position in which they are shown in FIG. 1 of the drawing. In this position of the unloader plunger 99, the fingers 104 carried by the flange 101 are in a position in which the springs 70 and 71 are eflective to seat the respective disc valves 80 and 81 on their corresponding valve seats 87 and 88 to thereby close communication between the chamber 62, which is connected by the pipe 68 to cylinder chamber 33 of the exhauster 7, and the atmospheric chamber 61.

Also, since fluid under pressure is completely vented from the chamber 132 in the release valve portion 10, as has been explained, a spring 136, disposed between a plug 137 and a vacuum release valve 138 in the release valve portion 10, is eifective to seat the vacuum release valve 138 to close a connection between the vacuum reservoir pipe 11, which is connected to the vacuum reservoir 5 now at atmospheric pressure and the vacuum brake pipe 3.

Similarly, since the operating piston 135 in the application valve portion 12 is subject only to atmospheric pressure, as has been explained, a spring 139, disposed between a plug 14-0 and a vacuum application valve 141 in the application valve portion 12, is effective to seat the vacuum application valve 141 to close a connection between a passageway 142 in the body 9 and atmosphere.

Now let it be assumed that the diesel engine which drives the exhausters 6 and 7 is started by means of the usual starting apparatus (not shown) provided on the locomotive for this purpose. Upon starting the diesel engine, the pistons 32 in the exhausters 6 and 7 will be reciprocated within the corresponding cylinder chambers 33. As the pistons 32 are moved downward from their uppermost or top dead center position to the position in which they are shown in FIG. 1 of the drawing, air at atmospheric pressure is drawn into the respective cylinder chambers 33 from the corresponding inlet valve chambers 37 through the ports 38 in the corresponding plugs 39 thereby reducing the pressure in the inlet valve cham bers 37 and cylinder chambers 33 below atmospheric pressure. As the pressure in inlet valve chambers 37 and cylinder chambers 33 is thus reduced below atmospheric pressure, atmospheric pressure acting on the upper side of the respective inlet valves 49 is effective to move these valves downward away from their seats 42 against the yielding resistance of the springs 50. Consequently, after the inlet valves 49 are thus unseated, air at atmospheric pressure is drawn from the vacuum reservoir through the pipe 44 and its respective branches connected to the passageways 43 in the cylinder heads 35 of the exhausters 6 and 7, thence through the passageways 43, past the now open valves 49, to the inlet valve chambers 37 and from thence into the cylinder chamber 33 in response to the vacuum created in these chambers by the downward movement of the pistons 32.

When the pistons 32 reach their lowermost or bottom dead center position, the cylinder chambers 33 will be filled with air at a pressure slightly below atmospheric pressure. Therefore, when the pistons 32 begin their upward or compression stroke, this air will be compressed to a pressure greater than atmospheric pressure, the pressure increasing as the pistons continue their upward stroke. The fluid thus compressed in the cylinder chambers 33 is effective to seat the'inlet valves 49 on their respective seats 42 and to unseat the discharge valves 53 when the pressure in the cylinder chambers 33 is increased sufficiently to overcome the opposing force of the springs 55.

When the discharge valves 53 are thus unseated, fluid under pressure will flow from the cylinder chambers 33 to the discharge valve chambers 51 and thence through the passageways 52 in the respective cylinder heads 35 to atmosphere.

Continued operation of the exhauster 6 and 7 will effect the withdrawal of fluid at a sub-atmospheric pres sure from the vacuum reservoir 5, the crankcase chambers 47 of each exhauster, and also the chamber 62 in the fluid pressure loading and unloading valve device 8 through the pipe 68 to reduce the sub-atmospheric pressure or increase the vacuum therein.

Simultaneously, as the exhausters 6 and 7 are pumping a vacuum in the vacuum reservoir 5, as just explained, the air compressor for supplying air under pressure to the main fluid pressure storage reservoir 1, which air compressor may be, as hereinbefore mentioned, one or more air compressing cylinders (not shown) forming a part of a compressor-exhauster unit, one exhauster cylinder being illustrated in FIG. 1 as the exhauster 7, is effecting the supply of fluid under pressure to the reservoir 1. As the pressure is thus increased in the main fluid pressure storage reservoir 1, fluid under pressure will flow therefrom through the supply pipe 29 to the feed valve device 2 and thence through the feed valve device 2 to the pipe 28. Fluid under pressure thus supplied to the pipe 28 will flow to the rotary valve chamber and thence to the chamber 132 in the release valve portion 10 of the brake control valve device 4 through a communication hereinbefore traced in detail.

Fluid under pressure thus supplied to the chamber 132 is eifective to move the operating piston 133 upward to unseat the vacuum release valve 138 against the yielding resistance of spring 136. When the vacuum release valve 138 is thus unseated, the vacuum reservoir pipe 11 is connected to the vacuum brake pipe 3. Therefore, as the exhausters 6 and 7 continue to operate to pump a vacuum in the vacuum reservoir 5, the vacuum brake pipe 3 also will be evacuated.

Now assume that one or more locomotive units are coupled to a train of cars having vacuum type brake equipment. The vacuum brake pipe 3 on each locomotive unit extends to each end of the unit. Therefore, if more than one unit is used to haul the' train, the ends of the vacuum brake pipe at abutting ends of the several units are connectedtogether by means of the usual hose couplings provided at each end of each unit, the end of the vacuum brake pipe at the front end of the leading unit is closed by means of the usual dummy coupling provided for this purpose, and the end of the vacuum brake pipe at that end of the last trailing unit that is adjacent the front end of the front car in the train is connected by means of the usual hose couplings to the end of the vacuum brake pipe at this end of the front car.

Since the end of the vacuum brake pipe at the opposite end of the front car is connected to the vacuum brake pipe extending serially through the other cars in the train to a dummy coupling at the end of the vacuum brake pipe on the last car, the brakes on all the cars will now be released as a result of evacuation of the vacuum brake pipe extending through the train, by operation of the exhausters 6 and 7.

When the vacuum in the vacuum reservoir 5 and the vacuum brake pipe extending from the locomotive unit or units through the cars in the train has reached the degree required to effect a complete release of the brakes on the train, which degree of vacuum will be made apparent to the locomotive engineer by suitable gages (not shown) located in the locomotive cab and connected, respectively, to the vacuum reservoir pipe 11 and the vacuum brake pipe 3, the locomotive engineer will move the handle 15 out of its Release and Charging position to its Running position.

As the handle 15 is turned, as just described, the rotary valve 13 is rotated therewith to a position corresponding to the Running position of the handle 15. The rotary valve 13 is so constructed that, with the handle 15 now in its Running position, a cavity 143 in the rotary valve 13, as indicated in FIG. 2 of the drawing, connects the port 21 in the rotary valve seat 17, which port 21 is connected, as has been hereinbefore explained, to the vacuum reservoir pipe 11, to the port 20 in the rotary valve seat 17, which port 20 is connected, as has been also hereinbefore explained, to the chamber 134 beneath the operating piston 135 in the application valve portion 12. Therefore, vacuum application valve 141 will be maintained seated by spring 139.

Furthermore, in this position of the rotary valve 13, fluid under pressure which has been supplied from the feed valve device 2 through the pipe 28 and branch 25a to the rotary valve chamber flows therefrom through a first passageway 144, which extends through the rotary valve 13 from one face thereof to the opposite face, as shown in FIG. 2, and registers with the port 19 in the rotary valve seat 17, to chamber 132 beneath the operating piston 133 in the release valve portion.

The rotary valve 13 has therein a second passageway 145, which passageway at one end opens into the first passageway 144. The rotary valve 13 also has therein two other passageways 146 and 147. Each of the passageways 146 and 147 opens at one end into the passageway 145 adjacent the end opposite the end opening into the passageway 144. The opposite ends of the passageways 146 and 147 register respectively with the ports 24 and 25 in the rotary valve seat 17. Therefore, when the rotary valve 13 is in the position shown in FIG. 2, fluid under pressure is supplied from the rotary valve chamber through the passageways 144, 145 and 147 to the port 24 in the rotary valve seat 17, which port 24, as has been hereinbefore explained, is connected to the chamber 131 in the fluid pressure operated loading and unloading valve device 8. Fluid under pressure is also supplied from the feed valve 2 to the port 25 in the rotary valve seat 17, as has been hereinbefore explained, and thence through the passageway 146 to the passageway 145. By supplying fluid under pressure to the passageway 145 from the rotary valve chamber and also from the port 25, an adequate supply of fluid under pressure is insured to the chamber 132 beneath the operating piston 133 in the application valve portion 10 to maintain the vacuum release valve 138 unseated and to promptly operate the fluid pressure operated loading and unloading valve device 8 to unload the exhauster 7 in a manner which will now be explained.

The fluid under pressure supplied to the chamber 131 above the piston 118 in the fluid pressure operated loading and unloading valve device 8 is elfective to move the unloader piston 118 downward against the yielding resistance of the spring 91 which acts through spring seat 92, unloader plunger 99, spring 105, spring seat 107 and cupshaped member 110 to oppose downward movement of piston 118. As the unloader piston 118 is thus moved downward, the unloader plunger 99 together with the fingers 104 carried by the flange 101 formed on the lower end of the plunger 99 are moved downward also, so that the fingers 104 move the annular disc valves 80 and 81 away from their respective seats 87 and 88. The annular disc valves 80 and 81 are thus moved downward by the fluid under pressure acting on the unloader piston 118 until these valves contact the shoulders formed by the lower end of the respective counterbores 78 and 79 in the spring retaining member 74.

When the annular disc valves 80 and 81 are moved away from their respective seats 87 and 88, as just explained, the cylinder chamber 33 in the exhauster 7 is connected to atmosphere through passageway 69, pipe 68, threaded bore 67, chamber 62, past the unseated valves 80 and 81, cavities 72, 73 and bores 76 and 77 in the spring retaining member 74, chamber 61 and passageway 65. Consequently, as the exhauster 7 continues to be driven by the diesel engine after the cylinder chamber 33 therein has been connected to atmosphere, air at atmospheric pressure is drawn into the cylinder chamber 33 on each downward stroke of the piston 32 of the exhauster 7 and is then forced from the cylinder chamber 33 back to the atmosphere on each upward stroke of this piston. It is therefore apparent that the exhauster 7 is now operating unloaded and is inetfective to assist the exhauster 6 in maintaining a vacuum in the vacuum reservoir and the vacuum brake pipe extending through the cars in the train.

Since the vacuum brakes on the cars in the train were completely released prior to moving the handle of the manually operated brake control valve device 4 out of its Release and Charging position to its Running position, the operation of the exhauster 6 in a loaded condition, while the exhauster 7 operates unloaded, will maintain the required degree of vacuum in the vacuum reservoir 5 and the vacuum brake pipe extending through the train necessary to insure that the train brakes are not applied by leakage from atmosphere into the vacuum brake pipe.

It is apparent from FIG. 1 that operation of the exhauster 6 in a loaded condition, while the exhauster 7 operates unloaded, is effective to maintain a sub-atmospheric pressure in the crankcase chamber 47 of the exhauster 7. Hence, the upper face of the piston 32 of the exhauster 7 is subject to atmospheric pressure and the lower face of this piston is subject to a sub-atmospheric pressure during the time that the exhauster 7 operates unloaded. Accordingly, this difference in pressure on the opposite faces of the piston 32 imposes a differential fluid pressure on the piston which acts in the direction from the cylinder chamber 33 toward the crankcase chamber 47 to reduce the susceptibility of lubricating oil to pass from the crankcase chamber to the cylinder chamber of the exhauster 7 so long as the exhauster 7 is operated unloaded.

If the train is running over track in substantially level terrain, one or more hours may elapse between the release and an application of the brakes during which time the exhauster 7 will operate unloaded. Thus, the imposition of a differential fluid pressure on the piston 32 of the exhauster 7 acting in a direction to diminish the susceptibility of the lubricating oil in the crankcase chamber 12 47 to pass from this chamber around the piston rings 34 carried by the piston 32 to the cylinder chamber 33 while the exhauster 7 operates unloaded results in an appreciable saving in the cost of lubricating oil during the life of the exhauster which may extend over a period of approximately twenty-five years.

Having now described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In a railway train vacuum brake system, in combination, a vacuum train pipe for controlling the application and the release of brakes according to the degree of vacuum in said vacuum train pipe, a vacuum reservoir, a multi-position brake control valve device for, in one position, establishing a communication between said vacuum train pipe and said vacuum reservoir to effect a release of brakes and for, in another position, establishing a communication through which fluid at atmospheric pressure is admitted to said vacuum train pipe to reduce the degree of vacuum therein to effect an application of brakes, a fluid exhauster comprising an exhausting cylinder, a piston reciprocable in said exhausting cylinder to effect evacuation of fluid from said vacuum reservoir, and a passageway opening into said exhausting cylinder above the top dead center position of said piston, a fluid pressure operated unloading valve device comprising valve means normally closing a communication between said passageway and atmosphere to effect loading of said fluid exhauster, and operable to open the communication for the admission of fluid at atmospheric pressure through said passageway into said exhausting cylinder to effect unloading of said fluid exhauster, and a source of fluid under pressure, said multi-position brake control valve device being effective in said one position to release fluid under pres sure from said fluid pressure operated unloading valve device and being effective in said another position to supply fluid under pressure from said source of fluid under pressure to said fluid pressure operated unloading valve device.

2. In a railway train vacuum brake system as claimed in claim 1, further characterized in that said brake system comprises two fluid exhausters to effect evacuation of said vacuum reservoir, and that only one of said two fluid exhausters is loaded and unloaded in response to the operation of said fluid pressure operated unloading valve device.

3. In a railway train vacuum brake system as claimed in claim 1, further characterized in that said fluid exhauster has a crankcase chamber constantly connected to said vacuum reservoir whereby a sub-atmospheric pressure is always maintained in said crankcase chamber independently of the position of said multi-position brake control valve device, and said sub-atmospheric pressure or atmospheric pressure is maintained in said exhausting cylinder accordingly as said multi-position brake valve device effects a release of brakes or effects an application of brakes.

4. In a brake control system for railway trains, provided with vacuum type brakes, in combination:

(a) a vacuum reservoir,

(/5) a vacuum brake pipe normally charged to a preselected low sub-atmospheric pressure, an increase from which initiates a brake application,

(0) a piston type fluid exhauster having an exhausting chamber through which evacuation of fluid from said vacuum reservoir is effected,

(d) a conduit connecting said vacuum reservoir and the exhausting chamber of said fluid exhauster through which fluid is conveyed from said vacuum reservoir to the exhausting chamber in response to reciprocation of the piston of said fluid exhauster within the exhausting chamber thereof,

(6) a passageway opening into the exhausting chamber above the top dead center position of the piston of said fluid exhauster,

(f) a super-atmospheric pressure operated unloading valve device connected to said passageway for nor- 13 mally closing communication between said passageway and atmosphere and operable in response to the supply of fluid under pressure thereto to open communication between said passageway and atmosphere whereby the exhausting chamber is open to atmosphere to unload said fluid exhauster,

(g) a source of fluid under super-atmospheric pressure,

and

(h) a manually operated multi-position engineers brake control valve device disposed between said vacuum reservoir and said vacuum brake pipe for manual operation to a release position in which fluid under pressure is vented from said super-atmospheric pressure operated unloading valve device to effect closing of communication between said passageway and atmosphere to load said piston type fluid exhauster, and in which communication is opened between said vacuum reservoir and said vacuum brake pipe whereby evacuation of said vacuum reservoir in response to operation of said piston type fluid exhauster effects evacuation of said vacuum brake pipe to cause a brake release, and for manual operation from said release position to a running position in which fluid under pressure is supplied from said source of fluid under pressure to said super-atmospheric pressure operated unloading valve device to effect the operation thereof to open the exhausting chamber of said piston type fluid exhauster to atmosphere to unload said piston type fluid exhauster and in which communication between said vacuum reservoir and said vacuum brake pipe is maintained whereby the vacuum in said vacuum reservoir is effective to maintain the train brakes released in the running position of said manually operated engineers brake control valve device.

5. In a brake control system for railway trains provided with vacuum type brakes, in combination:

(a) a vacuum reservoir,

(b) a vacuum brake pipe normally charged to a preselected low sub-atmospheric pressure, an increase of the pressure in which initiates a brake application,

(c) a fluid exhauster comprising, in combination:

(i) an exhausting cylinder,

(ii) a piston reciprocable in said exhausting cylinder to effect evacuation of fluid from said vacuum resesrvoir,

(iii) an inlet valve operable to admit fluid from said vacuum reservoir into said exhausting cylinder on the intake stroke of said piston,

(iv) a discharge valve past which fluid under pressure is discharged from said exhausting cylinder on the discharge stroke of said piston,

(d) a conduit connecting said vacuum reservoir and said inlet valve through which fluid is conveyed from said vacuum reservoir via said inlet valve to said exhausting chamber in response to reciprocation of said piston within said exhausting chamber,

(e) a passageway opening into said exhausting chamber above the top dead center position of said piston,

(f) a super-atmospheric pressure operated unloading valve device connected to said passageway for nori4 mally closing a communication extending between said passageway and atmosphere, and operable in response to the supply of fluid under pressure thereto to open the aforesaid communication whereby said exhausting chamber is opened to atmosphere to unload said fluid exhauster,

(g) a source of fluid under super-atmospheric pressure, and

(h) a manually operated multi-position vacuum type engineers brake control valve device disposed between said vacuum reservoir and said vacuum brake pipe for manual operation to a release position in which fluid under pressure is vented from said superatmospheric pressure operated unloading valve device to effect closing of a communication between said passageway and atmosphere to load said fluid exhauster and in which a communication is opened between said vacuum reservoir and said vacuum brake pipe whereby evacuation of said vacuum reservoir in response to reciprocation of said piston in said exhausting cylinder effects evacuation of said vacuum brake pipe to cause a brake release, and for manual operation from said release position to a running position in which fluid under pressure is supplied from said source of fluid under pressure to said super-atmospheric pressure operated unloading valve device to effect the operation thereof to open said exhausting chamber to atmosphere to unload said fluid exhauster and in which a communication between said vacuum reservoir and said vacuum brake pipe is maintained whereby the vacuum in said vacuum reservoir is effective to maintain the train brakes released in the running position of said manually operated multi-position vacuum type engineers brake control valve device.

6. In a brake control system for a railway train provided with vacuum type brakes, as claimed in claim 5, further characterized in that said fluid exhauster further comprises a crankcase chamber that is constantly connected without restrictions to said vacuum reservoir whereby the same sub-atmospheric pressure is always maintained in said crankcase chamber as is present in said vacuum reservoir irrespective of the pressure in said exhausting cylinder.

7. In a brake control system for a railway train provided with vacuum type brakes, as claimed in claim 5, further characterized in that said fluid exhauster further comprises a crankcase chamber that is constantly connected without restrictions to said Vacuum reservoir whereby said vacuum reservoir and said crankcase cham ber are evacuated in response to reciprocation of said piston within said exhausting cylinder and are subsequently maintained at a sub-atmospheric pressure upon cessation of admittance of fluid from said vacuum reservoir by said inlet valve into said exhausting cylinder in response to operation of said super-atmospheric pressure operated unloading valve device to admit fluid at atmospheric pressure into said exhausting cylinder to unload said fluid exhauster.

No references cited. 

1. IN A RAILWAY TRAIN VACUUM BRAKE SYSTEM, IN COMBINATION, A VACUUM TRAIN PIPE FOR CONTROLLING THE APPLICATION AND THE RELEASE OF BRAKES ACCORDING TO THE DEGREE OF VACUUM IN SAID VACUUM TRAIN PIPE, A VACUUM RESERVOIR, A MULTI-POSITION BRAKE CONTROL VALVE DEVICE FOR, IN ONE POSITION, ESTABLISHING A COMMUNICATION BETWEEN SAID VACUUM TRAIN PIPE AND SAID VACUUM RESERVOIR TO EFFECT A RELEASE OF BRAKES AND FOR, IN ANOTHER POSITION, ESTABLISHING A COMMUNICATION THROUGH WHICH FLUID AT ATMOSPHERIC PRESSURE IS ADMITTED TO SAID VACUUM TRAIN PIPE TO REDUCE THE DEGREE OF VACUUM THEREIN TO EFFECT AN APPLICATION OF BRAKES, A FLUID EXHAUSTER COMPRISING AN EXHAUSTING CYLINDER, A PISTON RECIPROCABLE IN SAID EXHAUSTING CYLINDER TO EFFECT EVACUATION OF FLUID FROM SAID VACUUM RESERVOIR, AND A PASSAGEWAY OPENING INTO SAID EXHAUSTING CYLINDER ABOVE THE TOP DEAD CENTER POSITION OF SAID PISTON, A FLUID PRESSURE OPERATED UNLOADING VALVE DEVICE COMPRISING VALVE MEANS NORMALLY CLOSING A COMMUNICATION BETWEEN SAID PASSAGEWAY AND ATMOSPHERE TO EFFECT LOADING OF SAID FLUID EXHAUSTER, AND OPERABLE TO OPEN THE COMMUNICATION FOR THE ADMISSION OF FLUID AT ATMOSPHERIC PRESSURE THROUGH SAID PASSAGEWAY INTO SAID EXHAUSTING CYLINDER TO EFFECT UNLOAD- 